First time Mac user here.

I'm quite aware with all the posts here about repartitioning hard disk but I'm quite confused if repartitioning would erase all my data on my hard disk.

I recently bought my Mac and it was pre-installed with Lion, and my hard disk size is 750GB, and under in one partition only. I would like to divide the disk into at least 2 partitions where I can put my music files so that it would be easier to backup with any backup/imaging software.

With my current setup, it means that I have a recovery partition on my disk that would allow me to reinstall Lion if problems would occur.

If it would erase all existing data on the disk if I repartition it, then my only choice is to do this:

1) Backup first my data using Time Machine 2) Boot from the recovery partition and erase and partition (3) the hard disk 3) Restore the image to the disk to the desire partition

What do you guys think?

1 Answer 1


Make sure to back up all of your data first, just in case.

Next, create a USB Recovery HD (at least 1GB) with these Apple forum instructions:

Create a USB thumb drive Recovery HD using the Lion Recovery Disk Assistant. Download this and install it. Then, insert a thumb drive and create your bootable Recovery HD. Last, boot from the USB thumb drive and from inside the Recovery HD on that, try the resize.

You should be able to resize your main partition after booting from the USB Recovery HD.

Another option is to use the Recovery HD on your Mac, as noted in the solution that @bmike suggested in another question - boot to your Recovery HD and use Disk Utility there to resize.

The solution that you've mentioned will work, but is a bit more work.

  • Is it dangerous to resize my hard disk if I'm currently using it? Let's say for example that I don't have any spare USB drives and hard disk available, can I still resize hard disk while I'm currently using it?
    – Panoy
    Commented Jul 27, 2012 at 1:39
  • @Panoy, you can do it, but I'll just say that I personally wouldn't do any major operations on my drive (upgrade OS, resize the partitions, etc.) without doing a backup. Everyone has a different level of risk tolerance.
    – JW8
    Commented Jul 27, 2012 at 17:26
  • I'll have to try this Lion Recovery Disk Assistant just as you have said. Currently I tried using the Recovery HD of my Mac and started to resize the current partition and added 3 ones, but the Disk Utility says that it can't unmount the disk. So therefore no resizing for me. I'm stuck with the whole 750GB HD of 1 partition only. I'll see if the Lion Recovery Disk Assistant using a USB will work. :D
    – Panoy
    Commented Aug 8, 2012 at 3:39
  • Thanks the Lion Recovery Disk Assistant did work. Happy now to have not only one partition.
    – Panoy
    Commented Aug 8, 2012 at 4:33

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .